Respuesta :

Answer:

3x.....

Step-by-step explanation:

Answer:

27

Step-by-step explanation:

Each next number is increased by 3. We already have 5 of the 9 numbers, so do find the ninth number quickly, do this:

  1. 9 - 5 = 4
  2. 4 × 3 = 12
  3. 15 + 12 = 27

I hope this helps!